Engine has a tick

[jrsick]

2006 5.0 I/O with carburetor. I've got a distinct ticking noise coming from area under the valve cover on the port side. Sound is aft, from cylinders 5 or 7.
I need advice to ensure I check this out the correct way. I thought I would first check the lead wires for jumping sparks, then check that spark plugs are secure.
Then, do you think it would be good idea to add engine treatment to the oil and see if that would help, perhaps free some sticky lifter?
If no luck at that point, I would remove valve cover and check for loose rods.
Your recommendations, advice, or questions are most welcome.
Randy

[mmwjr]

Most likely a lifter or too much valve train clearance.

Try removing the suspected cylinder spark plug wires one cylinder at a time to see if the noise changes. If it does you know which cylinder has the issue.

You can try the treatment. A warm valve stem, colpased lifter, or the rocker stud could have pulled out some as they are pressed in.

[speedysprocket]

Should be easy enough to pull the valve cover and feel the rockers for each valve while it's closed.

[mmwjr]

Forgot to mention a tick could also be an exhaust leak.

Manifold to cylinder head.

[jrsick]

Thank you Mike and Speedy.
For the lifter/rocker recommendations, should my first step be to look at the rockers and see if there is a rod with play or a nut that is backed off? I have some understanding of rockers and rods, but have never adjusted lash myself.
For exhaust leak, how do I check for that? I have a stethoscope, but not sure where to check.
Speedy, what part of Chesapeake are you in? I'm in Great Bridge. My boat is in OBX though so I have to plan out all the tools I need before driving down.

Randy

[mmwjr]

There is no lash adjustment on this engine. One torques the rocker to spec the the valve is in the closed position, see manual for details.

If you pull the valve cover you can check the push rods for play but the valve must be in the closed position for each one which means you'll need to rotate the crank. To make this easier remove the spark plugs to remove compression. There is risk that is low you can break the bolt on the balancer when turning the engine however if you turn it counter clockwise the bolt should unscrew instead of break if the rotating resistance is to high. Again removing the spark plugs will make this much easier.

SBC exhaust manifold has little gap to the head, use a tissue and hold it laid out around each port to the head if there is a leak the tissue will wave like a flag.

[speedysprocket]

There may be a kit to make the rockers adjustable, but if you need that, something is wrong and needs to be replaced. I only did that on my 7.4 because they surfaced both the block and heads and I thought it might be too much.
I live in Great Bridge, too. Off Cedar Rd. Boat is at NOB marina.

[jrsick]

I appreciate your inputs.
I will dive into SELOC and start work on Sunday morning. Let me know if there is a better manual than SELOC.

[mmwjr]

Originally Posted by jrsick

I appreciate your inputs.
I will dive into SELOC and start work on Sunday morning. Let me know if there is a better manual than SELOC.

There is its the mercruiser manual which can be found under Documents of this site.

[jrsick]

Mike,
I saw the documents, but looked to me like they were dated 1999. I wasn't sure if info was same for my 2006.
I downloaded the Mercruiser manual and read section on valves. It says valve lash is one turn down from zero lash. But you have info that says torque from zero lash. Do you think both are same torque levels?

[mmwjr]

Originally Posted by jrsick

Mike,
I saw the documents, but looked to me like they were dated 1999. I wasn't sure if info was same for my 2006.
I downloaded the Mercruiser manual and read section on valves. It says valve lash is one turn down from zero lash. But you have info that says torque from zero lash. Do you think both are same torque levels?

One turn from zero lash is correct, I was thinking Ford on the torque spec. Was a Mustang guy in my youth guess hard to get Chevy embraced in my older years.

[jrsick]

I think you've forgotten more about engines than I have ever known.
I start troubleshooting tomorrow and will post my progress.

[speedysprocket]

Originally Posted by mmwjr

One turn from zero lash is correct, I was thinking Ford on the torque spec. Was a Mustang guy in my youth guess hard to get Chevy embraced in my older years.

Are his rockers adjustable? The big blocks aren't.

[mmwjr]

Originally Posted by jrsick

I think you've forgotten more about engines than I have ever known.
I start troubleshooting tomorrow and will post my progress.

Lol

[mmwjr]

Originally Posted by speedysprocket

Are his rockers adjustable? The big blocks aren't.

Nope the stock rockers are not adjustable.

[jrsick]

Originally Posted by mmwjr

Forgot to mention a tick could also be an exhaust leak.

Manifold to cylinder head.

I'm glad you remembered to mention exhaust leak because that is what I think it is.
I put stethoscope all along the valve covers and valves were smooth.
Found noise where port manifold meets engine block (cylinder head).
I think fix for this is new gasket. Merc manual only says install exhaust manifold gasket and torque to 25 lbs in discussions on assembly and disassembly. No guide on replacing just the gasket. Doesn't even have picture of this gasket in parts breakdown.

Has anyone replaced just the gasket? I'm wondering if I have to remove riser and elbow to replace the exhaust manifold gasket.
What is the effect of a leaking exhaust gasket, other than noise and fumes?

I appreciate the good comments and discussion on my problem. Mike and Speedy have been very helpful.

[speedysprocket]

Yes, it all comes off. You'll need new manifold gaskets and elbow (and riser if you have that too) gaskets. Pretty straight forward. Remove everything (manifold is heavy) clean surface with razor blade, and reassemble. I replaced all my manifold bolts with stainless and used some anti seize.
So where in OBX is the boat and have you ever taken it to or from Hampton Roads?

[mmwjr]

Yes you'll need to remove the riser and manifold to get at the head to scrape away the old gasket from the head and manifold. Removing the riser requires a new gasket and cleaning as well. If old gasket is left behind it can cause a leak as the new one may not seal properly. Cheap fix and fairly easy labor.

Not fixing allows fresh air to be sucked in by backpressure which raises exhaust temps and can burn the exhaust valve. Also leaking exhaust gases are a safety risk for you.

[jrsick]

Thanks for the responses. Some questions to help plan repair:
- Do I need to separate the riser and manifold, or can I remove as a pair? I know this will be heavy. I have replaced riser gasket before and it was a challenge. I used Permatex to hold gasket in place but still had to get riser on just right the first time.
- Did you remover exhaust hose (rubber tube) from the riser, or keep it connected to riser? I'm trying to think of method that will result in least damage to hose.
- Should I address any corrosion issues I encounter? I have some excellent lightweight rust inhibitor.
regards and thanks, Randy

Speedy,
I keep my boat at a house in Southern Shores area of OBX most of the year. I boat the Currituck and Albemarle sounds. Lots of coves for fishing, crabbing, and water sports. Boat is at my house two months a year and I launch out of Bob's and Munden Point.
What is the name of your boat? I am at NOB Marina regularly. I would like to admire your fine vessel during next dock walk.

[mmwjr]

The manifold and riser can be removed in one piece and the hose can be either disconnected from the riser or from its other end.

How old is the exhaust and is the water you boat in brackage or salt? If either it may be time to replace anyhow.

Corrosion should always be addressed.

Being 2006 it may have dryjoint, do you know?